API RP 2003-2015 pdf download.Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents.
3 Terms, Definitions, Acronyms, and Abbreviations 3.1 Terms and Definitions For the purposes of this document, the following definitions apply. 3.1.1 arc An electrical discharge that occurs at the instant two points, through which a large current is flowing, are separated. Technically, electrostatic discharges are always sparks, not arcs. 3.1.2 bonding The practice of providing electrical connections between isolated conductive parts of a system to preclude voltage differences between the parts (see Figure A.5). The low current associated with static charges can be satisfactorily bled off using small wires over long distances. In field use, a strong wire resistant to physical damage may be needed, in which case a bond wire may be sized for physical or mechanical strength. These larger wires typically have low resistance. The process of connecting two or more conductive objects together by means of a conductor so that they are at the same electrical potential does not necessarily mean they are at the same potential as the earth. NOTE A bond resistance as high as 1 megohm (10 6 ohms) can be adequate for static dissipation. However, for stray current protection, lightning protection, and other electrical systems, the bonding resistance needs to be significantly lower, no more than a few ohms. 3.1.3 closed connection A connection in which contact is made before flow starts and is broken after flow is completed (e.g. bottom loading of tank trucks). 3.1.4 combustible liquid A liquid with a flash point at or above 100 °F (38 °C) as defined by NFPA 30. 3.1.5 conductivity σ The capability of a substance to transmit electrostatic charges, normally expressed in picoSiemens per meter (pS/m) or conductivity units. For petroleum products, the following conductivities are defined for the liquid temperature during transfer operations. Conductivity measurements at laboratory temperature shall be adjusted to represent transfer temperature using rationale such as explained in Annex B.6. 3.1.6 conductivity unit C.U. A unit of electrical conductivity equal to 1 pS/m where 1 pS/m = 1 × 10 –12 siemens per meter = 1 × 10 –12 ohm –1 m –1 . (The pS/m unit represents the same conductivity value as the now obsolete picomho/m.) 3.1.7 flammable liquid A liquid as defined by NFPA 30 having a flash point below 100 °F (38 °C) and having a Reid vapor pressure (RVP) not exceeding 40 psia (276 kPa). 3.1.8 grounding NFPA 77 defines grounding as the process of bonding one or more conductive objects to the ground, so that all objects are at zero (0) electrical potential (also referred to as “earthing”). For hydrocarbon transfers this is accomplished by providing electrical continuity between a fuel handling system and ground or earth to ensure that the fuel handling system is at zero potential (see Figure A.6). A resistance as high as 1 megohm is adequate for static dissipation. For other purposes, such as electrical systems, lightning protection, etc., very much lower resistances are needed. 3.1.9 hazard A situation or inherent chemical or physical property with the potential to do harm (flammability; oxygen deficiency; toxicity; corrosivity; stored electrical, chemical, or mechanical energy). 3.1.10 high vapor pressure products Liquids with a Reid vapor pressure 100 °F (38 °C) above 4.5 psia (31 kPa). These products include aviation and motor gasoline and high vapor pressure naphtha. 3.1.11 intermediate vapor pressure products Flammable liquids with a Reid vapor pressure 100 °F (38 °C) below 4.5 psia (31 kPa) and a closed-cup flash point of less than 100 °F (38 °C). These can form flammable vapors at ambient operating temperatures. Examples of these products are commercial aviation fuel (Jet B), military aviation turbine fuel (JP-4, TF-4), and solvents such as xylene, benzene, and toluene. 3.1.12 low vapor pressure products Liquids with closed cup flash points above 100 °F (38 °C).